He pulled down on a polished wooden lever that lay against the vertical arm. A round blade emerged from a cavity on the underside of the raised box, and locked into position with a quiet click at the end of the lever’s arc.

There was a slosh: the creature, in its boneless motion, was pacing in the bucket. He glanced at it.

‘Remarkable organism, the octopus. Three hearts, circulating blood that is blue, not red. Why? Because it contains copper, in all likelihood to carry oxygen in the same way our blood does.’

I smiled and nodded, because I was fairly sure that was the reaction he was seeking. ‘And if we accept the idea that the heart is the seat of the emotions, Doctor Gideon, what does one do with three of them?’

He laughed, sat before the table with his feet underneath and pedalled smoothly. The bellows started to breathe and the little round blade began to spin, fast enough that it emitted a whining sound. Using another timber lever, this one located on the side of the table, Gideon was able to lower the arm down to his working surface. He stopped briefly and directed a lamp that stood on his main desk so that it would illuminate what he was doing.

‘Do you like it?’ he asked. He gestured at the machine, his knees rising and falling, his face almost boyishly proud.

‘To be quite honest it looks like a sewing table.’

He was crestfallen, and I felt instantly ashamed.

‘That’s because it started out as a sewing table. I added the saw mechanism and the adjustable levers, the bellows.’ He gestured at them as if he could not comprehend why this was not impressive. ‘It’s a pneumatic saw—I know of no other example in the world. The blade operates at such high revolutions that it can cut through adamantine surfaces without the need to apply any force. Is that not remarkable to you?’ He made a helpless gesture, clearly hurt.

Now he took the nautilus shell from where it sat on his bookshelf, placed it under the blade and put his spectacles on. I came closer. He was lowering the blade gradually using the lever, and with his other hand aligning the shell so that the path of the blade would trace its long axis precisely. As the blade came into contact with the shell the whining became a scouring sound, amplified by the cavity of the shell. He ran the shell through in one smooth pass, and a plume of white dust rose in the lamplight, powdering his jaw and settling on the lenses of his spectacles.

‘This is the beauty of the saw,’ he said. ‘If I tried to pass a knife through this shell, no matter how sharp or careful, the shell would shatter.’